Photoelectric transducer device including a transistor including an oxide semiconductor layer

Abstract

An object is to obtain a rectifier having a small voltage drop and to reduce the fabrication cost of a converter circuit. A photoelectric transducer device including: a photoelectric transducer element; and a converter circuit stepping up or stepping down an output of the photoelectric transducer element and including a switching element and a rectifier, in which the switching element is a first oxide semiconductor transistor that is normally off and in which the rectifier is a second oxide semiconductor transistor that is diode-connected and normally on.

What is claimed is: 
     
       1. A photoelectric transducer device comprising:
 a photoelectric transducer element comprising electrodes; and 
 a converter circuit comprising:
 a coil comprising:
 a first terminal; and 
 a second terminal; 
 
 a first transistor comprising:
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the first transistor including indium and oxide; 
 
 a second transistor comprising:
 a gate electrode; 
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the second transistor including indium and oxide; and 
 
 a capacitor comprising electrodes; 
 
 wherein one of the electrodes of the photoelectric transducer element is electrically connected to the first terminal of the coil, 
 wherein the second terminal of the coil is electrically connected to the first terminal of the first transistor, the gate electrode, and the first terminal of the second transistor, 
 wherein the second terminal of the first transistor is electrically connected to the other of the electrodes of the photoelectric transducer element, and one of the electrodes of the capacitor, and 
 wherein the second terminal of the second transistor is electrically connected to the other of the electrodes of the capacitor. 
 
     
     
       2. The photoelectric transducer device according to  claim 1 , wherein the converter circuit is a DC-DC converter. 
     
     
       3. A photoelectric transducer device comprising:
 a photoelectric transducer element comprising electrodes; and 
 a converter circuit comprising:
 a coil comprising:
 a first terminal; and 
 a second terminal; 
 
 a first transistor comprising:
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the first transistor including indium and oxide; 
 
 a second transistor comprising:
 a gate electrode; 
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the second transistor including indium and oxide; and 
 
 a capacitor comprising electrodes; 
 
 wherein one of the electrodes of the photoelectric transducer element is electrically connected to the first terminal of the coil, 
 wherein the second terminal of the coil is electrically connected to the first terminal of the first transistor, the gate electrode, and the first terminal of the second transistor, 
 wherein the second terminal of the first transistor is electrically connected to the other of the electrodes of the photoelectric transducer element, and one of the electrodes of the capacitor, 
 wherein the second terminal of the second transistor is electrically connected to the other of the electrodes of the capacitor, and 
 wherein a film thickness of the channel formation region of the first transistor is different from a film thickness of the channel formation region of the second transistor. 
 
     
     
       4. The photoelectric transducer device according to  claim 3 , wherein the converter circuit is a DC-DC converter. 
     
     
       5. A photoelectric transducer device comprising:
 a photoelectric transducer element; and 
 a converter circuit comprising:
 a first transistor comprising:
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the first transistor including indium and oxide; 
 
 a second transistor comprising:
 a gate electrode; 
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the second transistor including indium and oxide; 
 
 a coil comprising:
 a first terminal; and 
 a second terminal; and 
 
 a capacitor comprising electrodes; 
 
 wherein one of the electrodes of the photoelectric transducer element is electrically connected to the first terminal of the first transistor; 
 wherein the second terminal of the first transistor is electrically connected to the gate electrode, the first terminal of the second transistor, and the first terminal of the coil, 
 wherein the second terminal of the second transistor is electrically connected to the other of the electrodes of the photoelectric transducer element, and one of the electrodes of the capacitor, and 
 wherein the second terminal of the coil is electrically connected to the other of the electrodes of the capacitor. 
 
     
     
       6. The photoelectric transducer device according to  claim 5 , wherein the converter circuit is a DC-DC converter. 
     
     
       7. A photoelectric transducer device comprising:
 a photoelectric transducer element; and 
 a converter circuit comprising:
 a first transistor comprising:
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the first transistor including indium and oxide; 
 
 a second transistor comprising:
 a gate electrode; 
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the second transistor including indium and oxide; 
 
 a coil comprising:
 a first terminal; and 
 a second terminal; and 
 
 a capacitor comprising electrodes; 
 
 wherein one of the electrodes of the photoelectric transducer element is electrically connected to the first terminal of the first transistor; 
 wherein the second terminal of the first transistor is electrically connected to the gate electrode, the first terminal of the second transistor, and the first terminal of the coil, 
 wherein the second terminal of the second transistor is electrically connected to the other of the electrodes of the photoelectric transducer element, and one of the electrodes of the capacitor, 
 wherein the second terminal of the coil is electrically connected to the other of the electrodes of the capacitor, and 
 wherein a film thickness of the channel formation region of the first transistor is different from a film thickness of the channel formation region of the second transistor. 
 
     
     
       8. The photoelectric transducer device according to  claim 7 , wherein the converter circuit is a DC-DC converter. 
     
     
       9. The photoelectric transducer device according to  claim 1 , wherein the coil is a coiled wire formed over a substrate over which the photoelectric transducer element and the converter circuit are formed. 
     
     
       10. The photoelectric transducer device according to  claim 1 , wherein the first transistor is normally off and the second transistor is normally on. 
     
     
       11. The photoelectric transducer device according to  claim 3 , wherein the coil is a coiled wire formed over a substrate over which the photoelectric transducer element and the converter circuit are formed. 
     
     
       12. The photoelectric transducer device according to  claim 3 , wherein the film thickness of the channel formation region of the first transistor is smaller than the film thickness of the channel formation region of the second transistor. 
     
     
       13. The photoelectric transducer device according to  claim 3 , wherein the first transistor is normally off and the second transistor is normally on. 
     
     
       14. The photoelectric transducer device according to  claim 5 , wherein the coil is a coiled wire formed over a substrate over which the photoelectric transducer element and the converter circuit are formed. 
     
     
       15. The photoelectric transducer device according to  claim 5 , wherein the first transistor is normally off and the second transistor is normally on. 
     
     
       16. The photoelectric transducer device according to  claim 7 , wherein the coil is a coiled wire formed over a substrate over which the photoelectric transducer element and the converter circuit are formed. 
     
     
       17. The photoelectric transducer device according to  claim 7 , wherein the film thickness of the channel formation region of the first transistor is smaller than the film thickness of the channel formation region of the second transistor. 
     
     
       18. The photoelectric transducer device according to  claim 7 , wherein the first transistor is normally off and the second transistor is normally on. 
     
     
       19. A semiconductor device comprising:
 an input terminal; and 
 a converter circuit comprising:
 a coil comprising:
 a first terminal; and 
 a second terminal; 
 
 a first transistor comprising:
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the first transistor including indium and oxide; 
 
 a second transistor comprising:
 a gate electrode; 
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the second transistor including indium and oxide; and 
 
 a capacitor comprising electrodes; 
 
 wherein the input terminal is electrically connected to the first terminal of the coil, 
 wherein the second terminal of the coil is electrically connected to the first terminal of the first transistor, the gate electrode, and the first terminal of the second transistor, 
 wherein the second terminal of the first transistor is electrically connected to one of the electrodes of the capacitor, 
 wherein the second terminal of the second transistor is electrically connected to the other of the electrodes of the capacitor, and 
 wherein the coil is a coiled wire formed over a substrate over which the converter circuit is formed. 
 
     
     
       20. The semiconductor device according to  claim 19 , wherein the converter circuit is a DC-DC converter. 
     
     
       21. The semiconductor device according to  claim 19 , wherein the first transistor is normally off and the second transistor is normally on. 
     
     
       22. A semiconductor device comprising:
 an input terminal; and 
 a converter circuit comprising:
 a first transistor comprising:
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the first transistor including indium and oxide; 
 
 a second transistor comprising:
 a gate electrode; 
 a first terminal; 
 a second terminal; and 
 an oxide semiconductor layer including a channel formation region, the oxide semiconductor layer of the second transistor including indium and oxide; 
 
 a coil comprising:
 a first terminal; and 
 a second terminal; and 
 
 a capacitor comprising electrodes; 
 
 wherein the input terminal is electrically connected to the first terminal of the first transistor; 
 wherein the second terminal of the first transistor is electrically connected to the gate electrode, the first terminal of the second transistor, and the first terminal of the coil, 
 wherein the second terminal of the second transistor is electrically connected to one of the electrodes of the capacitor, 
 wherein the second terminal of the coil is electrically connected to the other of the electrodes of the capacitor, and 
 wherein the coil is a coiled wire formed over a substrate over which the converter circuit is formed. 
 
     
     
       23. The semiconductor device according to  claim 22 , wherein the converter circuit is a DC-DC converter. 
     
     
       24. The semiconductor device according to  claim 22 , wherein the first transistor is normally off and the second transistor is normally on. 
     
     
       25. The photoelectric transducer device according to  claim 1 , wherein each of the oxide semiconductor layer of the first transistor and the oxide semiconductor layer of the second transistor further include gallium and zinc. 
     
     
       26. The photoelectric transducer r device according to  claim 3 , wherein each of the oxide semiconductor layer of the first transistor and the oxide semiconductor layer of the second transistor further include gallium and zinc. 
     
     
       27. The photoelectric transducer device according to  claim 5 , wherein each of the oxide semiconductor layer of the first transistor and the oxide semiconductor layer of the second transistor further include gallium and zinc. 
     
     
       28. The photoelectric transducer device according to  claim 7 , wherein each of the oxide semiconductor layer of the first transistor and the oxide semiconductor layer of the second transistor further include gallium and zinc. 
     
     
       29. The semiconductor device according to  claim 19 , wherein each of the oxide semiconductor layer of the first transistor and the oxide semiconductor layer of the second transistor further include gallium and zinc. 
     
     
       30. The semiconductor device according to  claim 22 , wherein each of the oxide semiconductor layer of the first transistor and the oxide semiconductor layer of the second transistor further include gallium and zinc.